In order to exploit hydrocarbon well location, drilling, casing, cementing and perforating operations are sequentially carried out above a hydrocarbon geological formation comprising underground reservoir. During production, hydrocarbon fluids are extracted from the underground reservoir via the casing and production tubing. The knowledge of various physical parameters characterizing the reservoir, the geological formation and the fluids flowing into the casing/tubing is necessary in order to allow a controlled and optimized exploitation of the reservoir during the production operation.
Various reservoir monitoring techniques are known for long-term reservoir management. Typically, these techniques involve sensors permanently installed downhole and continuously measuring said physical parameters. Generally, the operation of the sensors requires power and transmission of measurements to surface equipments for further processing and use.
First types of system are wired systems comprising cables directly connecting each sensor to surface equipments. However, such wire systems have various drawbacks, in particular casing installation complication, cable connection reliability, cable wearing and breaking risk, cable damaging risk during perforation, safety, etc. . . .
Second types of systems are wireless system. Document EP 1 609 947 describes such a system comprising an interrogating tool moved within the internal cavity formed by the casing. The interrogating tool is linked to surface equipments by means of a conductive cable. The interrogating tool provides wireless power supply to the sensor and wireless communication with a data communication means coupled to the sensor. However, such a wireless system requires an interrogating tool which may be difficult to insert and move during production operation. Document WO 01/65066 and EP 0 964 134 describe another system in which an electrical signal is provided to the sensor by means of an insulated conduit in the well. The electrical signal enables power supply between the surface equipments and the sensors. Document WO 01/65066 further describe a downhole module comprising a spread spectrum transceiver for data transmission between a downhole module including sensors and the surface equipments. However, such a wireless system requires an electrically insulated conduit in the well and induction chokes in order to impede current flow on casing and tubing.